JP2595075Y2 - DC brushless motor failure detection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless motor (also referred to as a brushless motor), and more particularly to detection of an open-phase failure.

[0002]

2. Description of the Related Art DC brushless motors are based on brushless motors, are free from sparks, have little electrical noise,
Features such as maintenance-free, industrial equipment,
It is used in a wide range of fields such as precision equipment and home appliances.

[0003] DC brushless motors use permanent magnets for their rotors and are brushless, so there are few electrical failures. As electrical protection, those that provide overload protection based on motor current are known. It is about.

[0004]

However, for example, a DC brushless motor used for driving a crossing bar of a railroad crossing circuit breaker or a parking lot breaker has such a breaker arranged outdoors, and is therefore subject to lightning strikes or the like. Failures such as phase loss may occur.

However, in a multi-phase brushless motor of a three-phase full-wave system or the like, the rotation angle range in which the rotational force disappears even if one of the phases fails is small, and in many cases, the motor rotates apparently normally. This is called open phase rotation.

[0006] This open phase rotation eventually leads to a motor stop depending on the starting position. For example, when the starting position of the DC brushless motor is in the rotation angle range where there is no rotational force at the time of a lift command in a level crossing circuit breaker, the balance of the blocking rod is adjusted so as to be lowered by gravity. And traffic congestion may occur.

The present invention has been made in view of such circumstances, and has as its object to provide a failure detection device for a DC brushless motor that quickly detects open-phase rotation of the DC brushless motor.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention focuses on the waveform of a motor current at the time of phase loss rotation and detects the phase loss rotation. Is configured as in the following (1).

(1) A motor current detecting means provided between a DC brushless motor and its power supply, a low-pass filter for extracting a low-frequency component from an output of the motor current detecting means, and an output value of the low-pass filter is converted to the DC value. A DC comprising: a comparator for comparing a value corresponding to a predetermined value smaller than a lower limit value of a motor current at the time of normal rotation of the brushless motor; and a judging means for judging whether or not the motor is open-phase rotation based on an output of the comparator. Failure detection device for brushless motor.

[0010]

According to the configuration of (1), the low frequency component of the motor current is extracted and compared with a predetermined value. When the phase is out of phase, the phase output is repeated by repeatedly outputting "H" and "L" as the comparison outputs. Determine the rotation.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.
FIG. 1 is a block diagram of a "fault detecting device for a DC brushless motor of a railroad crossing circuit breaker" according to an embodiment, and FIG. 2 is a circuit diagram of an LPF (low-pass filter), an amplification, and a comparator unit of FIG. FIG. 3 is a main part waveform diagram when the shut-off rod is normally raised, and FIG. 4 is a main part waveform diagram when the shut-off rod is lowered.

As shown in FIG. 1, a current of a DC brushless motor (hereinafter referred to as a motor) 1 is detected by a motor current detecting resistor 2 connected between the motor 1 and one end of a power supply (not shown). The component is taken out by the LPF unit 3, amplified by the amplifying unit 4, and compared by the comparator unit 5 with a value corresponding to a predetermined value smaller than the lower limit value of the motor current during normal rotation of the motor.

At the time of normal rotation of the motor, the motor current flows as shown in 2a of FIG. 3 or 2b of FIG. 4 (a), and is taken out from the LPF section 3 composed of an integrating circuit of a resistor 3-1 and a capacitor 3-2. The low frequency component never goes to zero.
The positive input terminal of the operational amplifier 5-3 is set to a value corresponding to a predetermined value smaller than the lower limit value of the motor current during normal rotation of the motor by the resistors 5-1 and 5-2. During normal rotation, the output terminal of the operational amplifier 5-3 remains at "L" and does not invert to "H", so that S1 in FIG. 3 and S1 in FIG. It becomes as shown in.

If one of the three phases is lost, the motor current flows as shown at 2c in FIG. 4B (the waveform differs depending on the motor circuit configuration and the location of the failure), and the output of the LPF unit 3 is intermittent. Becomes zero. As a result, the output terminal of the operational amplifier 5-3 becomes "H" intermittently as shown in S1 of FIG.

In the CPU 6, during the driving of the motor, the open phase rotation is determined by repeating "H" and "L" of the signal S1 for a predetermined time.

As described above, when the CPU 6 detects the phase loss rotation, the CPU 6 displays the rotation and displays an alarm and performs other processing.

In the embodiment, the determination of the phase loss rotation is made by the CPU.
However, the present invention is not limited to this, and may be performed by hardware.

In the embodiment, the motor current is extracted by a resistor. However, the present invention is not limited to this. For example, the motor current may be extracted by a current transformer.

[0019]

[Effects of the Invention] As described above, according to the present invention,
Open phase rotation of the DC brushless motor can be detected quickly.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a circuit diagram of an LPF, an amplification, and a comparator unit in the embodiment.

FIG. 3 is a waveform diagram of a main part when the shut-off rod is ascended normally.

FIG. 4 is a main part waveform diagram when the blocking rod is lowered.

[Explanation of symbols]

 Reference Signs List 1 DC brushless motor 2 Motor current detection resistor 3 LPF unit 5 Comparator unit 6 CPU

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Takano 1-13-8 Kamikizaki, Urawa-shi, Saitama Nihon Signal Co., Ltd. Yono Office (56) References JP-A-55-49921 (JP, A) JP-A-63-56190 (JP, A) JP-A-63-206187 (JP, A) JP-A-2-159994 (JP, A) JP-A-4-29594 (JP, A) JP-A-4-55163 (JP, A) JP-A-4-19053 (JP, A) JP-A-6-13397 (JP, U) JP-A-6-21395 (JP, U) JP-A-6-22148 (JP, U) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) B61L 29/00-29/32 H02H 7/06-7/093 H02P 6/00-6/24

Claims (1)

(57) [Scope of request for utility model registration] 1. A motor current detecting means provided between a DC brushless motor and its power supply, a low-pass filter for extracting a low-frequency component from an output of the motor current detecting means, and an output value of the low-pass filter, A comparator for comparing a value corresponding to a predetermined value smaller than a lower limit value of the motor current at the time of normal rotation of the motor; and determination means for determining whether or not the motor is open-phase rotation based on an output of the comparator. Characteristic DC brushless motor failure detection device.